The research proposed would develop a system of integrated tests that would include stagnation point flow (SPF) experiments and the testing of materials in aortic flow by means of a magnetic suspension device (MSD). The MSD technique, which has been pilot-tested in vitro by simulated systems but has not been tested in animals to date, would involve the use of a small cylindrical object (5 cm long and 0.5 cm in diameter) magnetically suspended in a coil system which can be placed around the aorta so that the cylinder is suspended centrally within the artery without touching the artery wall. Task I, Development of the in vivo MSD System, Task II, Biomaterials evaluation, short term tests using the established SPF technique to study platelet adhesion and morphology, white cell adhesion, and thrombus formation on candidate materials, and routine in vivo tests involving proposed MSD technique to study thrombus formation and embolization.